Mating Systems and Reproductive Strategies in Three Australian Gryllid Crickets: Bobilla victoriae Otte,Balamara gidya Otte and Teleogryllus commodus (Walker) (Orthoptera: Gryllidae: Nemobiinae; Trigonidiinae; Gryllinae)

The behaviour of B. victoriae and B. gidya in simulated natural habitats is described. Regular predictable sequences of behaviour are represented by ethograms. The mating systems of B. victoriae and B. gidya are compared with that of T. commodus which shows a sedentary call-and-reside strategy. B. victoriae shows an elaborated male call-search strategy while in B. gidya the male strategy is one purely of searching rather than advertising for mates. Males of B. victoriae and B. gidya were less territorial and less aggressive than males of T. commodus. Males of B. victoriae attracted females and monopolized them for repeated matings by providing what might be a nutritional resource in the form of multiple spermatophores which females were allowed to eat soon after copulation. Males of B. gidya produced fewer but much larger spermatophores than males of B. victoriae or T. commodus and females of B. gidya became unreceptive after mating. The reproductive strategies of the three species are analyzed in terms of environmental variables.     

Nuptial Flight in two Ponerine Ants,Pachycondyla Impressa and P. Fauveli,Overlooking Machu Picchu,Peru

We report on a simultaneous nuptial flight of ants of two sympatric ponerine species, Pachycondyla impressa and P. fauveli, on the top of Huayna Picchu (2700 m), Peru. After flying in and landing on the flat, hare rocks of the summit, the conspecific sexuals approached, antennated and mated without any previous female calling behaviour. During one hour of observation, the number of approximately 30 ♂ ♂ and ♀ ♀ Pachycondyla impressa and 70–86 of P. fauveli on the site remained constant because of individuals continuously arriving and leaving. Although nuptial flight seems to be the most common type of mating system in ants, this is one of the very few reports on the occurrence of this behaviour in ponerine species.     

Strategies of mate finding in the European field cricket (Gryllus campestris) at different population densities: a field study

Abstract. 1. Members of a field population of Gryllus campestris L. varied in their walking and calling activity. In both sexes, some individuals occupied burrows whereas others walked around in the observation area. Males at burrows could be either silent or calling.
2. In the course of one summer, population density decreased and the initial balanced sex ratio changed to a large surplus of males.
3. At high population density, there were equal numbers of non-calling males at burrows, calling males at burrows and walking males, while walking females predominated over females at burrows. Non-calling males at burrows achieved more encounters with females than did calling and walking males. Females met males by walking through the population and by waiting at burrows. Thus, calling and phonotaxis were not essential for mate finding and calling was less effective than previously thought.
4. At low population density calling males predominated. Calling males at burrows achieved the most encounters with females. Females met males only by walking around in the population area. Calling was thus more important in mate finding than at high population density.
5. Changes in sex ratio and population density may cause the flexibility in mate finding behaviour of individual crickets.     

Inbreeding and courtship calling in the cricket Teleogryllus commodus

Male field crickets produce two acoustic signals for mating: advertisement calls and courtship calls. While the importance of advertisement calling in mate attraction is well understood, the function of courtship calling is less clear. Here, we tested if the courtship call of male crickets Teleogryllus commodus signals aspects of male quality by comparing the calls of inbred and outbred males. We examined the effect of one generation of full sibling mating on fine‐scale call structure, along with several life history traits. Inbreeding reduced nymph survival but had no significant effect on weight or development time. Inbreeding resulted in a small but significant change in two of the six call parameters measured. We then tested if inbreeding affects call trait combinations that are important to females by using the results of a previous selection analysis to compare the multivariate attractiveness of the calls of inbred and outbred males. There was no difference. We conclude that the courtship call of T. commodus is not a reliable signal of aspects of male quality that are affected by inbreeding (which generally reduces fitness‐enhancing traits). It might, however, signal components of male fitness that are not affected by changes in heterozygosity.     

Sexual Interference and Sexual Defense in the Smooth Newt,Triturus vulgaris (Amphibia,Urodela, Salamandridae)

• 1 When a male smooth newt encounters a ♀ who is already engaged in courtship, he may mimic her behaviour during the spermatophore deposition and transfer stages of the courtship. He thereby usurps the courting ♂ and may inseminate the ♀ himself. Such sexual interference depresses the short-term, and perhaps long-term, mating success of the courting ♂.
• 2 In the presence of a potential rival, the courting ♂ alters certain aspects of his sexual behaviour. He displays more intensely to the ♀ and attempts to draw her away from the rival by increasing the duration of his display. He may also “check” that it is the ♀, and not the rival, who will elicit the deposition of a spermatophore from him. These changes in the behaviour of the courting ♂ are interpreted as defense against sexual interference.
• 3 Female smooth newts may be multiply inseminated as a consequence of sexual interference; this may result in sperm competition. However, ♀♀ seem to find competitive interactions between ♂ ♂ “aversive”.
• 4 Sexual interference by ♀-mimicry and associated defensive behaviour patterns are common in the urodele amphibians. Interference can be thought of as a “side-payment” conditional mating strategy.

     

Gecko phonotaxis to cricket calling song: A case of satellite predation

Insectivorous Mediterranean house geckos, Hemidactylus tursicus, are found in the field close to the burrows of calling male decorated crickets, Gryllodes supplicans. In playback experiments where adult geckos were presented with calls of these crickets or calls of frogs as controls, geckos exhibited positive phonotaxis to broadcast cricket calling song. This indicates that geckos orient to and approach male cricket calls, even though the crickets call from burrows where they are protected from the geckos. However, this behaviour enables the geckos to intercept and consume female crickets that also respond phonotactically to the cricket calls. Thus geckos act as ‘satellite predators’, a situation which may impose sex-biased mortality on female crickets.     

Auditory pattern recognition and steering in the cricket Teleogryllus oceanicus

Male crickets Teleogryllus oceanicus (Le Guillou) produce a complex species‐specific calling song with phrases combining groups of single pulses (chirps) and groups of double‐pulses (trills) to attract females, which fly or walk towards singing males. In open‐loop trackball experiments, phonotactic steering responses to normal calling song phrases consisting of chirps and trills are strongest, suggesting that both components are necessary for maximal attractiveness. Sequences of just chirps or trills are less effective in eliciting phonotactic walking and steering. Split‐song paradigms are used to analyze the steering behaviour underlying orientation in more detail. The females' phonotactic steering reflects the alternating acoustic pattern of the split‐song paradigm. Analysis with high temporal resolution demonstrate, that even when the calling song is presented only from one side, the steering velocity and lateral deviation towards the song is modulated by steering events to single‐sound pulses. Therefore, pattern recognition, which integrates the structure of the song, appears not to be directly involved in the rapid steering response. This organization of phonotactic behaviour with a parallel processing of pattern recognition and steering is similar to other cricket species and may allow T. oceanicus females to steer transiently towards distorted song patterns as they occur in natural habitats.     

Filtering of temporal parameters of the calling song by cricket females of two closely related species: a behavioral analysis

The phonotactic response of cricket females was investigated on a locomotion compensator to determine the temporal parameters of the male's calling song which are important for species recognition. Two sympatric species (Teleogryllus commodus, T. oceanicus) that show different syllable periods in the chirp and trill parts of their calling songs were used. By their responses T. commodus females exhibited two temporal filters for syllable periods, which were tuned to the species-specific syllable periods occurring during chirp and trill. For song recognition both filters had to be activated and for both a minimum number of three to five consecutive syllable periods was necessary. In contrast, T. oceanicus females showed only one sharply tuned filter corresponding to the chirp part of the male's calling song. This filter was sufficient for calling song recognition. Syllable periods of the trill part also influenced calling song recognition, but these played only a minor role. Carrier frequency was also important for positive phonotaxis. Calling song recognition by T. commodus females is largely based on central nervous processing, while for T. oceanicus both peripheral frequency filtering and central temporal filtering is important. Accepted: 17 January 1997     

Hybridization and F1 backcrosses between two closely related tropical species of sea urchins (genus Echinometra) in Okinawa

Summary

Four species of sea urchins of the genus Echinometra, designated species A, B, C, and D, occur along the coast of Okinawa; they are distinguished by color pattern and other characteristics. The two most distinct species, Echinometra sp. A (Ea) with white-tipped spines and Echinometra sp. D (Ed) with nearly black spines (possibly E. oblonga), were examined for potential hybridization through a series of fertilization experiments and rearing of the resulting hybrids. Fertilization was reciprocally asymmetrical; Ed ova were readily fertilized by sperm of Ea, but less than 20% of the ova of Ea were fertilized by sperm of Ed. Nevertheless, hybrids resulting from crosses in both directions developed normally through larval and juvenile stages to produce sexually mature adults. Larvae of Ed♀×Ea♂ and Ed♂×Ed♀ were larger than those of Ea♂ × Ed♀ and Ea♂ × Ea♀, reflecting the larger eggs of Ed. However, Ea♂×Ea♀ juveniles and later stages, up to maturity, were consistently larger than those of equivalent ages of the other crosses; largest to smallest were Ea♂×Ea♀, Ed♂×Ea♀, Ea♂ × Ed♀, and Ed♂×Ed♀, respectively. Ova and sperm of the hybrids were viable and fertilizable in all combination of crosses, although fertilization of those of Ed♂×Ea♀ hybrids was consistently higher than those of Ea♂ × Ed♀ hybrids. These experiments represent the first reported successful production of hybrid sea urchins with viable gametes. They indicate that reproductive isolation is achieved by prezygotic isolating mechanisms in these two species. Of these mechanisms, gametic incompatibility is probably only partly involved, if at all, and differences in spawning times, habitat segregation, or other factors appear to be important for maintaining reproductive isolation in these closely related species.     

INBREEDING AND ADVERTISEMENT CALLING IN THE CRICKET TELEOGRYLLUS COMMODUS: LABORATORY AND FIELD EXPERIMENTS

If sexually selected traits reveal a male's heterozygosity or condition to females, then such traits should exhibit declines with inbreeding. We tested this by examining the effect of inbreeding on advertisement calling in male crickets Teleogryllus commodus. We investigated the effect of one generation of full‐sibling mating on calling effort and fine‐scale call structure. Inbreeding reduced calling effort but had no effect on call structure. We then compared the attractiveness of inbred and outbred calls in the field by monitoring how many wild females were attracted to each call type. From the field data, we conducted a selection analysis to identify the major axes of linear and nonlinear multivariate sexual selection on call structure. A comparison of multivariate attractiveness of inbred and outbred calls along each major axis of selection revealed no difference in attractiveness. Our results suggest that inbred male calls have a fine‐scale structure that is no less attractive to females than that of outbred calls. However, because inbred males call less often, and female T. commodus prefer males with a higher calling effort, inbred males will suffer reductions in mating success. Females who base mate choice on call rate are therefore using a signal correlated with male heterozygosity and/or condition.     

Das Paarungsverhalten von Pycnopogon fasciculatus Loew (Diptera,Asilidae)

• 1 Bei der Raubfliege Pycnopogon fasciculatus vollführt das ♂ vor dem sitzenden ♀ eine Flugbalz, die hauptsächlich anhand von Filmaufnahmen analysiert wurde. Das ♂ schwebt bei der Flugbalz dicht vor dem ♀, schwenkt dann bis 10 cm nach hinten aus, um auf der gleichen Flugbahn stoßartig nach vorne vor das ♀ zu fliegen. Diesen Hin- und Herflug wiederholt das ♂ durchschnittlich 28mal. Zu Beginn der Flugbalz orientiert sich das ♂ durch Ertasten des weiblichen Vorderendes. Das ♂ hält die Beine an den beiden Umkehrpunkten der Flugbahn ganz verschieden (vgl. Abb. 2 c), zeigt aber keine Landehaltung. Flugtechnisch scheint die Veränderung der Beinstellung wenig Bedeutung zu haben. Ob die Beinhaltung vor dem ♀ aus einer ritualisierten Beuteübergabe hervorgegangen ist, bleibt offen. Das ♀ zeigt seine Abwehrbereitschaft bei der Flugbalz durch ritualisiertes Wackeln hochgehaltener Hinterbeine.
• 2 Das ♂ vollführt seine Flugbalz auch vor toten, artgleichen ♀ und ♂♂ und auch vor artfremden, z. T. größeren Fliegen. Die Flugbalz ist kürzer als vor lebenden ♀♀ (durchschnittlich nur 14 Anflüge) und führt wegen des Fehlens von Abwehrsignalen des ♂ doppelt so haufig zu einem unmittelbar anschließenden Kopulationsversuch.
• 3 Sitzende ♂♂ schlagen gegen anfliegende ♂♂ ihre Vorderbeine schnell abwechselnd in die Luft. Dieses Vorderbeinwirbeln tritt auch beim Schweben des ♂ vor dem ♀ während der Balz auf und wird als Abwehrhandlung gedeutet. Durch das Vorderbeinwirbeln gegen andere ♂♂ kommt es unter natürlichen Umständen nicht zur Flugbalz vor sitzenden ♂♂.
• 4 ♀♀ vertreiben arteigene ♀♀ und artfremde Fliegen häufig von ihrem Sitzast durch Anlaufen mit schräg angestellten, seitlich abgespreizten Flügeln.
• 5 Das ♂ versucht in 31 % der Fälle die Kopulation unmittelbar nach der Flugbalz (n = 96). Nicht Hochhalten der Hinterbeine des ♀ löst beim ♂ einen Kopulationsversuch aus. Die Kopulation dauert mindestens 15 min und vollzieht sich in der “end-to-end position”.
• 6 Das Paarungsverhalten von Pycnopogon fasciculatus läßt sich als Handlungskette darstellen (Tab. 2).
• 7 Das Paarungsverhalten der räuberischen, in einigen Fällen auch kannibalischen Asilidenfamilie ist sehr unterschiedlich. Außer Flugbalz ist Balz auf fester Unterlage und Überwältigung des ♀ durch das ♂ ohne vorausgehende Balzhandlungen bekannt.

     

In situ measurement of calling metabolic rate in an Australian mole cricket, Gryllotalpa monanka

Examination of the energetics of sound production usually requires measurement of species that will produce normal calls under unnatural circumstances. Such measurements are potentially compromised by stress-related changes in calling input (through a reduction in calling effort) or output (through forced use of sub-optimal singing burrows). To determine if such measurements are indeed affected by abstraction from a natural setting, we measured the energetics of song production in undisturbed mole crickets Gryllotalpa monanka and employed a new approach where the animal's singing chamber replaces the respirometry chamber normally used in studies of this type. It was therefore possible to measure metabolic rate (MR) of calling crickets in situ for animals within self-constructed burrows under natural conditions. Calling MR measured under these conditions averaged 13.5-fold higher than standard MR and 2.2-fold higher than MR measured during burrowing in the lab. The calling MR of G. monanka was similar to that measured for other calling insects, and to endothermic insects, but was only 10% of that allometrically predicted for a similarly sized insect (0.89 g) during flight. A male mole cricket is estimated to consume 5.9 ml of oxygen during construction of a calling burrow and a 1-h calling bout; by comparison, a flying female would consume a similar volume in less than 6 min.     

In situ measurement of calling metabolic rate in an Australian mole cricket, Gryllotalpa monanka.

Examination of the energetics of sound production usually requires measurement of species that will produce normal calls under unnatural circumstances. Such measurements are potentially compromised by stress-related changes in calling input (through a reduction in calling effort) or output (through forced use of sub-optimal singing burrows). To determine if such measurements are indeed affected by abstraction from a natural setting, we measured the energetics of song production in undisturbed mole crickets Gryllotalpa monanka and employed a new approach where the animal's singing chamber replaces the respirometry chamber normally used in studies of this type. It was therefore possible to measure metabolic rate (MR) of calling crickets in situ for animals within self-constructed burrows under natural conditions. Calling MR measured under these conditions averaged 13.5-fold higher than standard MR and 2.2-fold higher than MR measured during burrowing in the lab. The calling MR of G. monanka was similar to that measured for other calling insects, and to endothermic insects, but was only 10% of that allometrically predicted for a similarly sized insect (0.89 g) during flight. A male mole cricket is estimated to consume 5.9 ml of oxygen during construction of a calling burrow and a 1-h calling bout; by comparison, a flying female would consume a similar volume in less than 6 min.     

The Energetics of Male Mating Strategies in Field Crickets (Orthoptera: Gryllinae: Gryllidae)

Male field crickets (Gryllinae: Gryllidae: Orthoptera) vary in their mating strategies, particularly in whether they call from defended sites to attract phonotactic females or roam silently in search of potential mates. To better understand the economics underlying these alternative strategies, respirometry was employed to examine the energetic costs of each strategy's component behaviors for a representative species, Acheta domesticus. Advertisement calling in this species, composed of low pulse rate chirps, is an order of magnitude less energetically costly than walking per unit time. However, for gryllids that advertise call with higher pulse rate trills, calling and walking appear to be of equivalent energetic cost. Thus, if energetic costs are important in determining grylline mating strategies, trillers and chirpers should have different sensitivities to change in factors affecting the relative payoffs of each strategy. Field studies of changes in mating behavior with increased population density support this argument. This study also determined that courtship calling by A. domesticus was over twice as energetically costly as advertisement calling per unit time, suggesting its importance as a more reliable indicator of signaler, or mate, quality.     

Social Organization and Ecology of the Klipspringer (Oreotragus oreotragus) in Ethiopia

Der Klippspringer (Oreotragus oreotragus) wurde in drei Gebieten in Athiopien beobachtet. Meist leben ein ♂ und ein bis zwei ♀♀ zusammen. Die Gruppe hat ein kleines Wohngebiet (etwa 8 ha), das sie gegen andere Gruppen verteidigt. Klippspringer fressen meist Gras und Blätter von Büschen. Klippspringer haben viele Feinde. Das ♂ steht meist Wache, während das ♀ gesichert frißt. Das ♀ führt Ortswechsel an. Die Jungen werden nach der Regenzeit im November geboren. Im folgenden Jahr verlassen die männlichen Jungen ihre elterliche Gruppe; die weiblichen Jungen bleiben länger darin, und einige paaren sich mit ihrem Vater. Stabile Paarbindungen werden als Anpassung an offene Landschaft gedeutet; das ♂ kann ♀♀ und Junge beschiitzen.     

Influence of age and environmental factors on burrow-making behavior of the short-tailed cricket,Anurogryllus muticus (De Geer) (Orthoptera: Gryllidae)

For the short-tailed cricket, Anurogryllus muticus, burrow-making behavior is essential. All nymphal instars construct burrows, but in the adult stage the rate of burrowing behavior is age dependent. Increases in photophase and light intensity stimulate burrowing, and the explicit negative phototaxis is correlated with the cricket's inability to exist under dry conditions. Ingestion of substrate during burrow construction may serve to acquire additional moisture. There is no evidence of burrow recognition, and crickets can construct a burrow when needed. The natural distribution of burrows at the plot investigated on Moorea supports the notion thatA. muticus builds burrows where the preferred food plantAlysicarpus vaginalis is most abundant. By minimizing the traveling distance to food sources when foraging they can retreat to their burrow again.     

The effect of ultrasound on the attractiveness of acoustic mating signals

Abstract. Previous laboratory studies ( Nolen & Hoy 1986b ) have shown that the phonotactic responses of flying crickets are influenced by the relative intensities of attractive (mating signal) and repulsive (predator) stimuli. At the functional level, these results suggest that predator cues (ultrasound) can change the attractiveness of a calling song. Using extracellular recordings from cervical connectives it was shown that, like other field crickets, Gryllus rubens (south-eastern field cricket) is sensitive to ultrasound. This ultrasonic sensitivity has probably evolved in response to predation pressure from echolocating bats. Using acoustic playback under field conditions, it was tested whether the relative attractiveness of two male calling songs was influenced by the simultaneous broadcast of ultrasound. A simulated male calling song of G. rubens was broadcast at two different intensities (109 and 103 dB) from two sound traps that caught flying crickets attracted to the songs. Simulated bat ultrasound was broadcast simultaneously with the high-intensity calling song (109 dB) and the relative catch in each of the two traps was measured. The intensity of the ultrasound was varied on different nights. The relative attractiveness of the high-intensity sound trap decreased significantly as the intensity of the ultrasound broadcast with it was increased. For the lowest of the ultrasound broadcast levels, the relative attractiveness did not differ from that expected for two calling songs broadcast without ultrasound. Thus, increased levels of simulated predation risk decreased the attractiveness of the calling song associated with it. These are the first field experiments to show that predation risk in the form of simulated bat ultrasound influences the phonotactic behaviour of flying crickets.     

The calling song of the field cricket,Gryllus bimaculatus (de geer): constraints on transmission and its role in intermale competition and female choice

Field studies of calling male field crickets, Gryllus bimaculatus, showed that males formed calling aggregations. Within aggregations males appeared to maintain an exclusive female-attraction zone about their burrows; calling song may thus serve as an aggressive signal to neighbouring males to maintain spacing. Calling song attenuates with distance. Furthermore, calls became degraded with distance by the loss of low frequency components and a reduction in the interval between chirps and pulses due to reverberation. Playback experiments suggested that the predictable degrading properties of the call may serve as a distance-finding mechanism maintaining observed male spacing. The intensity of calls and the repetition rate of chirps and pulses was positively correlated with male size. While information contained within the intensity parameter of calls may prove unreliable due to unpredictable attenuation and irregular amplitude fluctuations, the repetition rate of chirps and pulses was not affected by distance degradation. Playback experiments in which intensity was controlled suggested that females orientate preferentially to the calls of large males.     

The disappearance of injected prostaglandins from the circulation of adult female australian field crickets,Teleogryllus commodus

During the first 2 h following injection of 0.02 μCi of [¹⁴C]-prostaglandin E₂ into the abdomen of adult virgin female crickets, T. commodus, the concentration of radioactivity in the circulating hemolymph decreases. The reduction is associated with the increase in radioactivity in the Malpighian tubule/hindgut complex, ovaries, fat body, and, to a much smaller extent, ventral nerve cord and flight muscles. The finding that most, but not all, of the radioactivity in the hindgut is located in the contents of the lumen suggests that a high proportion of prostaglandins circulating in the hemolymph of T. commodus is eliminated by the usual excretory pathway. We suggest that the differential uptake of label from the circulating hemolymph by various tissues may be related to possible physiological functions that remain to be discovered.